The present invention relates generally to radon testing packages containing a radon collecting material such as activated charcoal and, more particularly, to a radon testing package of more simplified construction with an increase in test accuracy. The subject radon testing package is an improvement over the package disclosed in Alvarez U.S. Pat. No. 4,847,494, the entire disclosure of which is hereby expressly incorporated by reference.
Radon is a heavy radioactive gaseous element, which exists naturally in the environment, and is found in most soil gases. Radon levels may vary considerably at different sites, and over time at any given site. Because naturally occurring radon levels are now known to sometimes be high enough to cause health concerns, various testing products have been introduced to aid in the detection of radon at a particular location. In general, some such radon detection products take the form of a sealable package of radon adsorption material, most commonly activated charcoal. The package is situated in an area to be tested and opened so that the activated charcoal is exposed to the ambient air for a measured testing period. At the conclusion of the testing period, the package is sealed. The activated charcoal or other radon adsorption material is later analyzed to determine the level of radon, if any, adsorbed thereby. In this manner, a given test site, such as a room or basement of a house or building, may be tested for the presence and/or level of radon therein.
Various factors give rise to variations in naturally-existing radon levels at any one time, such as atmospheric pressure changes. For example low pressure centers, such as storms, may draw higher levels of soil gas from the ground. Radon levels may change radically in the course of only a few hours. Thus it is desirable to have testing periods extend over several days, so that an average level of radon for a given test area is thereby determined. Such an average level accordingly reflects a truer indication of the potential annual radon levels at the test site.
The above-incorporated Alvarez U.S. Pat. No. 4,847,494 discloses a radon detecting package which has a somewhat balanced radon adsorption and retention characteristic so as to permit a practical testing period of about two days. The activated charcoal in that package design adsorbs during such a testing period an adequate amount of radon for detection purposes, usually without collecting a deleterious amount of moisture. While radon typically is rapidly taken on or adsorbed by commonly employed radon adsorption materials (e.g. activated charcoal) the adsorbed radon is subsequently driven off from the activated charcoal by the absorption of moisture as the test proceeds. The radon testing package of Alvarez U.S. Pat. No. 4,847,494 provides for a somewhat controlled amount of the ambient gases and water vapor to have access to a pouch of adsorption material during a testing period. Static ambient gases are allowed to adsorb onto the activated charcoal somewhat more slowly than the more common open designs thus effectively integrating the adsorption over an extended period.
More particularly in the radon testing package disclosed in Alvarez U.S. Pat. No. 4,847,494, a flexible generally flat packet is made of radon barrier material, and is expandable so as to define a cone-shaped chamber within the envelope which includes an opening for access to ambient gases. Supported within the flexible outer radon barrier material is a pouch made of a folded sheet of gas-permeable material, in particular, Tyvek.RTM., a paper-like product formed of non-woven polyethylene fibers. Tyvek.RTM. is a product of the E.I. DuPont Corporation, Wilimington, Del. Activated charcoal is enclosed within the Tyvek pouch, and is retained by heat sealing. In particular, the three unfolded edge portions of the Tyvek panel are heat sealed between corresponding edge portions of the flexible outer packet of radon barrier material during manufacture of the package. During such heat sealing, the material of the flexible outer packet prevents direct contact of the heat sealing tool against the Tyvek material.
For holding the packet open to establish a predetermined degree of access to ambient air to the pouch of activated charcoal, the package of Alvarez U.S. Pat. No. 4,847,494 employs a folded cardboard insert, which resembles a paper airplane. The "paper airplane" is inserted into the packet opening during a test, and subsequently removed.
For sealing the access opening at the conclusion of the test, the package disclosed in Alvarez U.S. Pat. No. 4,847,494 has an adhesive strip on a fold-over flap, which is used to seal the package in a manner similar to a conventional envelope, forming a self-mailer whereby the test package can conveniently be mailed to a testing laboratory for analysis.
While generally effective for its intended purpose, the radon testing package of Alvarez U.S. Pat. No. 4,847,494 nevertheless is subject to improvement, particularly in the area of cost reduction and automated manufacture.
In addition, a disadvantage of the radon testing package as disclosed in Alvarez U.S. Pat. No. 4,847,494 is that accurate test results may not be achieved in the presence of increased air currents. Air blowing on or near an activated charcoal sampler may increase its sensitivity to radon, yielding test results indicating erroneously high levels of radon. Accordingly, the instructions included with most radon testing packages state clearly that the device should not be placed in a draft, and should not be placed in the same room with any type of operating fan or blower. Despite these instructions, there nevertheless remains the possibility that some users may ignore the instructions, and conduct the test in the presence of abnormal air currents.